A motor controller can make or break your project, literally.
The last thing that you want to find out is that your motor controller can't do what you need it to or that it's actually not able to perform up to your real needs. Many people have little or no sense of how much power is needed to make the vehicle match their desired driving habits and many who have already converted a vehicle to electric lie about how well their vehicles perform. Be informed and get the right parts the first time, or suffer spending more for inferior performance. Please note that this article will be discussing controllers meant for series wound DC traction motors.
There are now several manufacturers making EV motor controllers, some of which have the bare minimum capabilities to function and others are so feature rich that they could (nearly) pass for what General Motors might install in a vehicle if they used series DC motors. Some of the most well known controllers are Zilla, Soliton, DC Power Raptor, WarP-Drive, Curtis, and Kelly; not mentioned are controllers that don't produce enough power to get a car up to freeway speed or are not well know enough at the time of this writing. Most of the manufacturers produce one or more controllers that satisfy the need for a low bill of materials and others may appear inexpensive, but have hidden costs and complexities.
Your first decision to to determine how much horsepower (HP) you can afford and whether you'll want to upgrade your system at a later time without spending a lot of money. I suggest purchasing the biggest, baddest controller you can afford, one that's capable of pushing more power than you'll need to (unless you're drag racing and will squeeze every last bit of power out no matter what). By purchasing the biggest, baddest controller, you avoid the common mistake of building an under powered EV and not being able to afford to do anything about it. Controllers like the Zilla 1K HV, WarP-Drive, Soliton & Soliton Jr., offer impressive voltage ranges, current outputs, and are not very expensive considering what they do. For vehicles under 2500 lbs, you should have your eye on controllers that put out a minimum of 125 HP. For vehicles between 2500 and 3500, your controller should put out 200+ HP. Vehicles over 3500 lbs. will need a controller capable of 250+ horsepower. Another way of looking at HP requirements is, for every 1000 pounds of vehicle, you should figure about 60+ HP. This will make sure that you're not putting extra stress on components when you are driving in harsh or tougher than normal conditions.
Also consider a controller that supports liquid cooling. Though many EVers love to brag about the absence of liquids coolant and oil in their vehicles, liquid cooling can help the electronics in your controller last longer (the Soliton Jr controller and controllers like it, will not fail as a result of the cooling system failing and to avoid failure, these controllers automatically derate output once the temperature of the device reaches a certain temperature). In the Soliton user manual, it is said that for every 50 degrees F you cool your electronics, you roughly double their lives. If the controller doesn't support liquid cooling, it may not be worth trying to add it later on. The liquid needs to pass near the parts in the power stage of the device in order to be most effective. Liquid cooling can also be used to shuffle heat from your controller and into other areas of the vehicle such as the batteries or cabin. I bought a cooling system meant for computers and installed it on my Soliton Jr., then routed the heat into the cabin to defrost the rear window.
Hidden costs will surface throughout your project, be it shocks that seemed would hold up to the rigors of a heavy EV, but don't, or a controller that needs an external contactor and precharge control. The Soliton controllers have contactors and precharge built in, which makes for clean wiring, ease of installation and lowers the relative cost of the product (I consider it worth at least $200 to have these parts built in). Be sure to read through the controller's manual before buying it, most of them are available online and are written knowing that EV novices will be using the manual (this is not to say that you'll easily understand everything in the manual).
Buying a used controller could be a good decision, depending on the cost, how old it is, how it was used/abused and whether the manufacturer or other company still supports the product. One website, EV Trading Post is a listing service wherein you can find used controllers. I almost bought a used Zilla 1k HV (asking price was $1800), but opted instead for the Soliton Jr., due the the relative price and features. I paid about the same ($2100) for a the Soliton JR., which had about the same voltage range, but lower peak current; what really sold me on the Soliton was the continuous power and internal contactor and precharge, among other features exclusive to Soliton.
Motor and battery protection features are very important in an electric motor controller. Most controllers have some sort of protection for both motors and batteries, but not all features are equal. Protection for batteries is very important for increasing their life. Many controllers have a LVC feature, which essentially turns off the controller when the battery voltage reaches a user configured value, but this feature can inhibit the amount of power taken from the batteries, thereby affecting available power. Only Soliton offers two separate values, one of which allows the pack voltage to drop during acceleration and the other will prevent you from over discharging the pack. Remember that you won't get the full power from your batteries until the voltage has sagged to half of the nominal value, so this feature is very important. Protecting the motor from over current or over speeding is a valuable feature of many controllers. Keep in mind that for over speed protection, you'll need a speed sensor on the motor and the sensor will be connected to the controller. Many motors come with a temperature snap switch, that will close a circuit of your choosing, which could be a light, alarm or input to the controller and the controller could be configured to properly respond to the switch closing a circuit in a high temperature event.
It's unwise to rush into ordering your EV parts. Taking your time and doing research enables you to find little things that can save time and money and are easily overlooked. Buying a controller is a big decision and since controllers are often able to handle enough power to destroy life and property, rushing could prove catastrophic.
You can find more info at locotranspo.com
The last thing that you want to find out is that your motor controller can't do what you need it to or that it's actually not able to perform up to your real needs. Many people have little or no sense of how much power is needed to make the vehicle match their desired driving habits and many who have already converted a vehicle to electric lie about how well their vehicles perform. Be informed and get the right parts the first time, or suffer spending more for inferior performance. Please note that this article will be discussing controllers meant for series wound DC traction motors.
There are now several manufacturers making EV motor controllers, some of which have the bare minimum capabilities to function and others are so feature rich that they could (nearly) pass for what General Motors might install in a vehicle if they used series DC motors. Some of the most well known controllers are Zilla, Soliton, DC Power Raptor, WarP-Drive, Curtis, and Kelly; not mentioned are controllers that don't produce enough power to get a car up to freeway speed or are not well know enough at the time of this writing. Most of the manufacturers produce one or more controllers that satisfy the need for a low bill of materials and others may appear inexpensive, but have hidden costs and complexities.
Your first decision to to determine how much horsepower (HP) you can afford and whether you'll want to upgrade your system at a later time without spending a lot of money. I suggest purchasing the biggest, baddest controller you can afford, one that's capable of pushing more power than you'll need to (unless you're drag racing and will squeeze every last bit of power out no matter what). By purchasing the biggest, baddest controller, you avoid the common mistake of building an under powered EV and not being able to afford to do anything about it. Controllers like the Zilla 1K HV, WarP-Drive, Soliton & Soliton Jr., offer impressive voltage ranges, current outputs, and are not very expensive considering what they do. For vehicles under 2500 lbs, you should have your eye on controllers that put out a minimum of 125 HP. For vehicles between 2500 and 3500, your controller should put out 200+ HP. Vehicles over 3500 lbs. will need a controller capable of 250+ horsepower. Another way of looking at HP requirements is, for every 1000 pounds of vehicle, you should figure about 60+ HP. This will make sure that you're not putting extra stress on components when you are driving in harsh or tougher than normal conditions.
Also consider a controller that supports liquid cooling. Though many EVers love to brag about the absence of liquids coolant and oil in their vehicles, liquid cooling can help the electronics in your controller last longer (the Soliton Jr controller and controllers like it, will not fail as a result of the cooling system failing and to avoid failure, these controllers automatically derate output once the temperature of the device reaches a certain temperature). In the Soliton user manual, it is said that for every 50 degrees F you cool your electronics, you roughly double their lives. If the controller doesn't support liquid cooling, it may not be worth trying to add it later on. The liquid needs to pass near the parts in the power stage of the device in order to be most effective. Liquid cooling can also be used to shuffle heat from your controller and into other areas of the vehicle such as the batteries or cabin. I bought a cooling system meant for computers and installed it on my Soliton Jr., then routed the heat into the cabin to defrost the rear window.
Hidden costs will surface throughout your project, be it shocks that seemed would hold up to the rigors of a heavy EV, but don't, or a controller that needs an external contactor and precharge control. The Soliton controllers have contactors and precharge built in, which makes for clean wiring, ease of installation and lowers the relative cost of the product (I consider it worth at least $200 to have these parts built in). Be sure to read through the controller's manual before buying it, most of them are available online and are written knowing that EV novices will be using the manual (this is not to say that you'll easily understand everything in the manual).
Buying a used controller could be a good decision, depending on the cost, how old it is, how it was used/abused and whether the manufacturer or other company still supports the product. One website, EV Trading Post is a listing service wherein you can find used controllers. I almost bought a used Zilla 1k HV (asking price was $1800), but opted instead for the Soliton Jr., due the the relative price and features. I paid about the same ($2100) for a the Soliton JR., which had about the same voltage range, but lower peak current; what really sold me on the Soliton was the continuous power and internal contactor and precharge, among other features exclusive to Soliton.
Motor and battery protection features are very important in an electric motor controller. Most controllers have some sort of protection for both motors and batteries, but not all features are equal. Protection for batteries is very important for increasing their life. Many controllers have a LVC feature, which essentially turns off the controller when the battery voltage reaches a user configured value, but this feature can inhibit the amount of power taken from the batteries, thereby affecting available power. Only Soliton offers two separate values, one of which allows the pack voltage to drop during acceleration and the other will prevent you from over discharging the pack. Remember that you won't get the full power from your batteries until the voltage has sagged to half of the nominal value, so this feature is very important. Protecting the motor from over current or over speeding is a valuable feature of many controllers. Keep in mind that for over speed protection, you'll need a speed sensor on the motor and the sensor will be connected to the controller. Many motors come with a temperature snap switch, that will close a circuit of your choosing, which could be a light, alarm or input to the controller and the controller could be configured to properly respond to the switch closing a circuit in a high temperature event.
It's unwise to rush into ordering your EV parts. Taking your time and doing research enables you to find little things that can save time and money and are easily overlooked. Buying a controller is a big decision and since controllers are often able to handle enough power to destroy life and property, rushing could prove catastrophic.
You can find more info at locotranspo.com
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